beneath the table to the abstract. Use the Word Count cmd under Utilites menu for counting Significance There is a substantial amount of socially-induced stress associated with being HIV positive, arising from multiple sources, including discrimination, stigmatization, and experience of bereavements. The degree to which individuals experience such stress has been proposed as one factor contributing to the enormous variability in disease progress. Objectives Using the SIV-macaque model of HIV infection, we are studying adult male rhesus macaques to determine whether individuals with different personality characteristics respond to social interaction differently, and whether their different responses are associated with variation in SIV-disease related measures. Results In the past budget year, we have constructed backpack devices that subjects in our experiment will wear, and pilot-tested them with one animal. The backpacks enable us to obtain heart rate, blood pressure, and blood samples from awake, unrestrained animals during social interaction, without their knowledge. The devices comprise of a microprocessor, battery, blood pressure transducer, valves for controlling blood flow from an indwelling catheter into sample collection tubes, and syringes for injecting heparin (for catheter maintenance) and ketamine (for immobilizing the animal for retrieval of the filled sample collection tubes). Future Directions In the next budget period, we will instrument three cohorts of four animals each, and observe the animals during social interaction with stimulus animals. Half of the animals will be high, and half will be low, on the personality dimension 'Sociability'. During all interaction sessions, we will collect behavioral and physiological data. Animals will be inoculated with SIV, and their disease tracked through 16 weeks post-inoculation, after which they will be euthanized. KEYWORDS SIV, AIDS, psychosocial, stress, individual differences FUNDING NIH Grant MH49033